The present invention relates to a radiation source wire member and its delivery apparatus effective in radiotherapy of cancers and tumors such as prostate cancer, breast cancer, etc.
The number of prostrate cancer patients has been increasing rapidly in Japan because of the recent Westernization of lifestyle and diet. Though the prostrate cancer is likely to provide such symptoms as urination disorder and hematuria, there are so many cases exhibiting no symptoms that it is difficult to find it out at an early stage.
The prostate cancer may be cured by the ablation of the affected part and a radiation therapy. However, the former treatment inficts large pain on the patients, while the latter treatment gives anxiety to them because the other organs are unnecessarily exposed to radiation.
Against this treatment, much attention has recently been paid to a close-distance radiation therapy (brachytherapy), by which the cancer-affected part of the body is treated by radiation from a source disposed close thereto. This method utilizes direct, low-energy radiation to the affected part, making patients feeling safe without pain as in surgical operation.
The latest brachytherapy in the U.S. uses radioactive seeds for low-energy radiation with 125I or 103Pd as a radiation nuclide.
FIG. 6(a) shows an example using 103Pd as a radiation nuclide, in which a radiation seed comprising graphite pellet 25 coated with 103Pd and an X-ray marker 23 made of lead is encapsulated in a titanium tube 20 of 0.8 mm in diameter and 4.5 mm in length with sealed ends.
FIG. 6(b) shows an example using 125I as a radiation nuclide, wherein a silver bar24 coated with 125I is encapsulated in a titanium tube 20 of 0.8 mm in diameter and 4.5 mm in length like FIG. 6(a). In the examples shown in FIGS. 6(a) and (b), these capsules are usually connected at a uniform interval to provide a train-connected radiation source, because of difficulty in the direct or accurate insertion into the cancer-affected part of the body. See FIG. 5(b).
However, this radiation source is disadvantageous not only in complicated structure and high production cost, but also in low radiation efficiency because radiation is effected through the titanium capsule. As shown in FIG. 5(b), the use of a train-connected radiation source results in nonuniform radiation onto the affected part of the body. In addition, because of a large diameter of a delivery needle (outer diameter: 1.9 mm), the body tissues are likely to be deformed or damaged.
Accordingly, it is optimum to use a radiation source in the form of a coiled wire low at production cost and excellent in radiation distribution, which is now under development, and a radiation means high in radiation efficiency and uniform in radiation distribution is obtained by subjecting a rhodium wire to a proton activation treatment to partly convert Rh to 103Pd, the activated rhodium wire being most desirably formed into a coil.
Accordingly, an object of the present invention is to provide a radiation source wire member effective for the brachytherapy of cancer and tumor such as prostate cancer, breast cancer, etc., particularly to a radiation source wire member comprising a radiation source constituted by a coiled wire of rhodium at least partly converted to 103Pd.
Another object of the present invention is to provide a delivery apparatus for indwelling the radiation source wire member in the cancer-affected part of the body.
As a result of intensive research in view of the above objects, the inventors have found that by using a coiled wire of rhodium partly converted to 103Pd as a radiation source wire member, and by inserting this member in a capsule if necessary, and further by charging it into a tubular delivery apparatus for brachytherapy, the member can be indwelled in the cancer-affected part of the body rapidly and accurately. The present invention is completed based on this finding.
The first radiation source wire member indwelling in the cancer-affected part of the body for radiotherapy according to the present invention comprises an indwelling tip end portion having a radiation source and a filament bonded to the indwelling portion, the filament having such a length that at least a rear end portion thereof is exposed outside the body after indwelling.
The second radiation source wire member according to the present invention comprises an indwelling tip end portion having a radiation source and a filament covered with a synthetic resin capsule, a rear end of the capsule being bonded to the filament having such a length that at least a rear end of portion thereof is exposed outside the body after indwelling.
The first apparatus for delivering the radiation source wire member to the cancer-affected part of the body for indwelling according to the present invention has a catheter structure comprising (a) an outer tube having an inner diameter permitting the indwelling portion to pass through without resistance, and (b) an inner tube received in the outer tube movably back and forth therein and having an inner diameter not permitting the indwelling portion to pass through but permitting the filament to pass through without resistance.
The second delivery apparatus for delivering the radiation source wire member to the cancer-affected part of the body for indwelling according to the present invention comprises a tube having an inner diameter permitting the radiation source wire member to pass through without resistance, and a plunger movably received in the tube for pushing the radiation source wire member out of a tip end of the tube.
The indwelling tip end portion has a radiation source preferably constituted by a coil of rhodium at least partially converted to 103Pd by a proton activation treatment.